Unsafe Canning Methods (2011)

There are no safe short cuts in canning.

Do not use any "novel" methods even if you have been told "it works" because there is no substitute for adequate heat treatment. Some people have had what may be called "good luck" for years, but each season is different and you never know when a season will be the one when everything spoils. This is because heat-resistant bacteria are not always present. When these organisms are absent, the under-processed foods might keep. If they are present, the food spoils. So you must always assume they are present.

The open-kettle method involves placing hot food in jars and sealing with no further heat treatment. This method is NOT recommended for home canning of any food. You should not use the method because it seldom sterilizes food. Without sufficient heat to destroy bacteria and sterilize the food, the product may spoil. Food may spoil if it gets contaminated when you transfer it from kettle to jar.

Foods ferment when open-kettle canning does not destroy yeasts, or permits them to enter the jar before it is sealed. Simply getting lids to seal on jars will not prevent food from spoiling.

Oven-canning is extremely hazardous. When you can food it is important to know and control temperature. With oven-canning the temperature will vary according to accuracy of the oven regulator, and how heat circulates. The dry heat penetrates food jars very slowly. Oven-canning can be dangerous regardless of the brand of oven, jar, cap or lid you use. Jars may explode, wrecking the oven and seriously cutting or burning someone. Most important, the temperature of the food in the jars during oven-canning is not high enough to destroy dangerous bacteria—particularly the ones that may cause deadly botulism poisoning.

Do not use any chemicals or preserving powders as a substitute for heat-treating home-canned food. These will not help prevent food from spoiling, or give you a good product. If you do not use a heat treatment, there will not be a vacuum in containers and this will generally accelerate food deterioration. The only safe procedures are the boiling-water bath process for acid foods and pressure-canning for low-acid foods.

For more information on this subject, Please visit the College of Agricultural Sciences Publications Web site.

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